This invention relates to electronic engraving devices for engraving ink-receiving cavities into the surface of a gravure printing cylinder. Such engraving devices commonly comprise an engraving head which includes a diamond stylus and a guide shoe. The guide shoe bears against the printing cylinder and provides a reference surface for the engraving process. An electromagnetic driver is mounted within the engraving head for oscillating the stylus into engraving contact with the printing cylinder. Meanwhile the printing cylinder rotates about its cylindrical axis. The engraving head is supported such that it moves parallel to the axis of the printing cylinder in synchronism with printing cylinder rotation. A typical prior art device is shown in Buechler U.S. Pat. No. 4,450,486.
A prior art device of the type disclosed in the Buechler patent supports the engraving head in a manner generally as illustrated in FIG. 1 hereof. Thus an engraving head 12 supports a guide shoe 13 against a print cylinder 10 which is rotating in the direction indicated by the arrow 11. Engraving head 12 rests upon a deck 16 which in turn is supported by a base 20. Base 20 is horizontally moveable as indicated by the arrow 15, while deck 16 is rotatable about an axis 18. Rotation of deck 16 about axis 18 produces rotational movement of engraving head 12 as indicated by the arrow 93. A diamond engraving stylus (not illustrated in FIG. 1) is mounted alongside guide shoe 13 and is brought into engraving contact against cylinder 10 by a combination of translational motion and rotary motion. During setup the rotational position angle of engraving head 12 is adjusted so as to align the guide shoe and engraving stylus to the cylinder surface and produce a desired printing cell depth for a predetermined stylus driving signal. Unfortunately the rotation of engraving head 12 changes the orientation of the stylus as well as its cutting depth. This produces unwanted engraving errors.
It is therefore seen that there is a need for engraving head support means capable of positioning a stylus against a printing cylinder by translational motion only.